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a fost răspuns

Sa aflam un numar, stiind ca inmultindul cu 2 supra 7 obtinem acelasi rezultat ca atunci cand scadem 30 din el

Răspuns :

Daniel998
x*[tex] \frac{2}{7} [/tex]=x-30

[tex] \frac{2x}{7} [/tex]=x-30

2x=7x-210
-5x=-210*(-1)
5x=210
x=210/5
x=42

Verificare:42*(2/7)=12 si 42-30=12
   
[tex]\displaystyle\\ x - 30 = x \cdot \frac{2}{7} \\\\ x - 30 = \frac{2x}{7} \\\\ x - \frac{2x}{7} = 30\\\\ \frac{7x}{7} - \frac{2x}{7} = 30\\\\ \frac{7x-2x}{7}= 30\\\\ \frac{5x}{7}= 30\\\\ 5x = 30 \cdot 7\\\\ x = \frac{30 \cdot 7}{5} = 6\cdot 7 = \boxed{\bf 42} [/tex]



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